186 TERTIARY INSECTS OF NORTH AMERICA. 



Length of body, 6.5 mm ; of front wing, 7 mm ; width of same, 2.85 mm . 

 Florissant. Seven specimens, Nos. 1027, 1718, 2677, 4633, 5433, 

 10900, 10953. 



7. DEROBKOCHUS CRATERS. 



PI. 13, Fig. 13; PI. 15, Fig. 4. 



A moderate-sized species, with dusky wings, the veins infuscated. The 

 body is moderately stout, but no parts are fairly preserved but the front 

 wings. These are moderately slender, the tip rounded, the apical margin 

 oblique and only a little full, the broadest part of the wing near the middle of 

 the outer half; the first apical cell (not shown in the figures) is very small, 

 considerably smaller than the third, which last is only a little more than 

 half as long as the second, which is slightly longer than its stalk ; discoidal 

 and median cells very long and slender and of about equal size. 



Length of body, 7-8.5 mm ; of front wings, 8 mm ; breadth of same, 2.6 mm ; 

 length of hind wings, 6 mm . 



Florissant. Four specimens, Nos. 2514, 5059, 14235 ; and from the 

 Princeton Collection No. 1.947. 



4. LITOBROCHUS gen. nov. (Azrd?, 



This name is proposed to include a single species of Florissant Hydro- 

 psychidse, allied to Polycentropus and Derobrochus, and especially the lat- 

 ter, but differing from them in some points in the neuration of the wing. 

 Like Derobrochus, there is no fifth apical cell in the front wing, thus clearly 

 separating it from Polycentropus. It differs from Derobrochus in the still 

 more intensified elongation of the interior cells, and in the minuteness of the 

 first apical cell, which is relatively not half so large as in any species of 

 Derobrochus. The anastomosis is also very widely separated, the median 

 cell extending far toward the margin and being half as long as the wing itself. 



LITOBROCHUS EXTERNATUS. 

 PI. 15, Fig. 10. 



A single specimen shows the body, fore legs, and front wings. It is a 

 tolerably large species with moderately slender body. The front legs are 

 small and the tibia bears a single pair of spurs. The front wings are slender, 

 broadest before the middle of the outer half, the apex produced and nearly 



